A metanode of different ways that people have divided up chunks of time:

• Abenaki calendar
• Ancient Greek calendar
• Ásatrú calendar
• Aztec calendar
• Babylonian calendar
• Bahá'í calendar
• Buddhist calendar
• Chinese calendar
• Chinese lunar calendar
• Coligny calendar
• Christian Star calendar
• Discordian calendar
• Druidic calendar
• Egyptian calendar
• French Revolutionary calendar
• Gregorian calendar
  • Everything Perpetual Calendar
  • February 29
  • How to calculate the day of the week for a given date
  • October 15, 1582
• Indian civil calendar
• Islamic calendar
• Jewish calendar
• Julian calendar
  • cal 9 1752
• Khoikhoi calendar
• Mayan calendar
  • The Haab
  • The Long Count
  • The Tzolkin
• Roman calendar
• Vaishnava calendar

Suggested calendar reforms

• 13 months calendar
• Barlow calendar
• Tranquility Calendar
• The World Calendar

Calendars from fictional works:

• Calendar of the Dwarves
• Celtic Tree calendar
• Gloranthan calendar
• Pendorian calendar
• Shire calendar
• Zork calendar

Inspired by Cyt's writeup calendrical system.